Production of Moulded Bodies From Lignocellulose-Based Fine Particle Materials

ABSTRACT

The present invention relates to a process for the production of moldings from finely divided materials based on lignocellulose, and the moldings obtainable thereby. The invention also relates to the use of aqueous compositions which comprise at least one crosslinkable urea compound for the preparation of finely divided materials based on lignocellulose and treated with this composition for the production of moldings.

The present invention relates to a process for the production ofmoldings from finely divided materials based on lignocellulose, and themoldings obtainable thereby. The invention also relates to the use ofaqueous compositions which comprise at least one crosslinkable ureacompound for the preparation of finely divided materials treated withthis composition and based on lignocellulose for the production ofmoldings.

Moldings based on finely divided materials based on lignocellulose (alsoreferred to below as moldings based on lignocellulose particles), suchas, for example, based on wood particles, are widely used asconstruction materials in the construction and furniture sectors. Theyare produced, as a rule, by glue-coating of the lignocellulose particleswith a liquid, usually aqueous composition of binder polymers, shapingof the materials thus glue-coated and curing. During the curing,adhesive bonding of the finely divided materials takes place, ifappropriate with crosslinking of the binder, with the result that themolding retains its stability. In the case of wood-plastic composites(WPC), the finely divided materials are embedded in a plastic matrix. Anoverview of the customary types of moldings based on lignocelluloseparticles and the processes for their production is given by H. H. Nimzet al, “Wood—Wood-based Materials”, in Ullmann's Encyclopedia ofIndustrial Chemistry, 5th Ed. on CD-ROM, Wiley-VCH, Weinheim 1997. Asmass-produced goods, moldings based on finely divided lignocelluloseparticles are subject to immense cost pressure.

A key problem in the case of moldings based on lignocellulose particlesis their frequently only moderate to low stability to water. Thisresults from the property of the lignocellulose particles to incorporatewater, for example into the cell walls, on contact with water or in ahumid atmosphere. As a result, the moldings swell and their mechanicalstrength is reduced. Moreover, moldings based on lignocelluloseparticles, in particular in the moist state, are attacked bywood-degrading or wood-discoloring organisms, in particularmicroorganisms, necessitating the treatment of the moldings withcorresponding fungicides and biocides. This in turn is a notinconsiderable cost factor and is also disadvantageous fromenvironmental points of view.

For improving the stability, wood and comparable lignocellulose-basedmaterials are frequently rendered water repellent, for example bytreatment with wax-containing impregnating agents. This makes it moredifficult for water to penetrate into the pores of the material.

It was proposed to improve the dimensional stability of wood-basematerials, such as particle boards and fiberboards, and their stabilityto wood-destroying organisms by acetylating the wood particles with theaid of anhydrides, such as acetic anhydride (cf. EP-A 213252 andliterature cited therein and Rowell et al., Wood and Fiber Science, 21(1), pages 67-79). The high costs of the treatment and the unpleasantintrinsic odor of the material thus treated are disadvantageous, so thatthese measures have not become established on the market.

Other chemicals too, such as isocyanates, siloxanes and acrylamide, wereproposed for the modification of lignocellulose fibers (J. Appl. PolymSci., 73 (1999) 2493-2505). However, these measures too are as a wholeunsatisfactory.

WO 2004/033170 and WO 2004/033171 describe the use of impregnatingagents based on hydroxymethyl- or alkoxymethyl-modified ureaderivatives, such as1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one,bis(hydroxymethyl)-4,5-dihydroxyimidazolidinone modified with alkanols,1,3-bis(hydroxymethyl)urea, 1,3-bis(methoxymethyl)urea,1-hydroxymethyl-3-methylurea, 1,3-bis(hydroxymethyl)-imidazolidin-2-one,1,3-dimethyl-4,5-dihydroxyimidazolidin-2-one ortetra(hydroxy-methyl)acetylenediurea, for improving the durability,dimensional stability and surface hardness of wood bodies comprisingsolid wood. The problem of the dimensional stability of moldings basedon finely divided lignocellulose materials is not discussed.

Accordingly, it is the object of the present invention to provide afinely divided material based on lignocellulose, from which materialmoldings having improved dimensional stability under the action ofmoisture can be produced. The finely divided material should moreover beeconomical to produce with regard to the use in the production ofmass-produced products, such as fiberboards and particle boards.

It was surprisingly found that this and further objects can be achievedby finely divided materials based on lignocellulose which were treatedwith an aqueous composition which comprises at least one crosslinkableurea compound, the crosslinkable urea compound being selected from ureacompounds H which have at least one N-bonded group of the formula CH₂OR,where R is hydrogen or C₁-C₄-alkyl, and/or a1,2-bishydroxyethane-1,2-diyl group bridging the two nitrogen atoms ofthe urea, precondensates of the urea compound H, and reaction productsor mixtures of the urea compound H with at least one alcohol which isselected from C₁-C₆-alkanols, C₂-C₆-polyols and oligoethylene glycols.

Below, finely divided materials based on lignocellulose are alsoreferred to as finely divided lignocellulose materials or lignocelluloseparticles for short. Accordingly, finely divided materials treatedaccording to the invention and based on lignocellulose are also referredto as treated lignocellulose materials or finely divided lignocellulosematerials according to the invention or as treated lignocelluloseparticles or lignocellulose particles according to the invention, anduntreated finely divided materials based on lignocellulose are alsoreferred to as untreated finely divided lignocellulose materials oruntreated lignocellulose particles.

Treatment is understood as meaning impregnation or soaking of theuntreated finely divided lignocellulose materials with the aqueouscomposition and, if appropriate, drying and/or curing of the impregnatedmaterial or the curable components absorbed by the impregnated material.

Finely divided lignocellulose materials which were impregnated with theaqueous composition of the crosslinkable urea compounds and which weretreated in a manner such that the crosslinking of the urea compounds(curing) has taken place give, on customary further processing, moldingswhich are distinguished by superior mechanical properties, in particularby improved shape stability or dimensional stability, i.e. less swellingon contact with moisture, and by a higher surface hardness. Moreover,the moldings are less susceptible to attack by wood-destroyingmicroorganisms, such as harmful wood-destroying fungi andwood-destroying bacteria, with the result that the application ofcorresponding fungicides and biocides can be reduced and frequently evenavoided. The crosslinking of the crosslinkable urea compounds of theaqueous composition is effected after the impregnation, optionally in aseparate drying/curing step at elevated temperature and/or during thesubsequent shaping process after the glue-coating with a bindercustomary for the production of moldings, if appropriate by addition ofa catalyst promoting the curing of the urea compounds.

Accordingly, the present invention firstly relates to the use of anaqueous composition, comprising at least one crosslinkable urea compoundfrom the group consisting of the urea compounds H which have at leastone N-bonded group of the formula CH₂OR, where R is hydrogen orC₁-C₄-alkyl, and/or a 1,2-bishydroxyethane-1,2-diyl group bridging thetwo nitrogen atoms of the urea, precondensates of the urea compound H,and reaction products or mixtures of the urea compound H with at leastone alcohol which is selected from C₁-C₆-alkanols, C₂-C₆-polyols andoligoethylene glycols, for the preparation of finely divided materialstreated with this composition and based on lignocellulose for theproduction of moldings.

The invention furthermore relates to the treated lignocellulosematerials thus obtainable and their use for the production of moldings.The invention also relates to the moldings produced using suchimpregnated lignocellulose materials.

Aqueous compositions of crosslinkable urea compounds of the type underdiscussion are disclosed, for example, in WO 2004/033170 and WO2004/033171 cited at the outset and in K. Fisher et al. “TextileAuxiliaries—Finishing Agents” Section 7.2.2 in Ullmann's Encyclopedia ofIndustrial Chemistry, 5th Ed. on CD-ROM, Wiley-VCH, Weinheim 1997, andliterature cited there, e.g. U.S. Pat. No. 2,731,364 and U.S. Pat. No.2,930,715, and are usually used as crosslinking agents for textilefinishing. Reaction products of urea compounds with alcohols, forexample modified 1,3-bis(hydroxymethyl)-4,5-dihydroxy-imidazolidin-2-one(mDMDHEU), are disclosed, for example, in U.S. Pat. No. 4,396,391 and WO98/29393. In addition, urea compounds H and their reaction products andprecondensates are commercially available, for example under the tradenames Fixapret® CP and Fixapret® ECO from BASF Aktiengesellschaft.

The urea compounds present in the aqueous compositions are low molecularweight compounds or oligomers having a low molecular weight which as arule are present completely dissolved in water. The molecular weight ofthe urea compounds is usually below 400 dalton. It is assumed that,owing to these properties, the compounds can penetrate into the cellwalls of the lignocellulose particles and, on curing, improve themechanical stability of the cell walls and reduce their swelling causedby water.

Examples of a crosslinkable urea compound of the curable, aqueouscomposition are the following, without being restricted thereto:

-   1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one (DMDHEU),-   1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one which is    modified with a C₁-C₆-alkanol, a C₂-C₆-polyol or an oligoethylene    glycol (modified DMDHEU or mDMDHEU),-   1,3-bis(hydroxymethyl)urea,-   1,3-bis(methoxymethyl)urea;-   1-hydroxymethyl-3-methylurea,-   1,3-bis(hydroxymethyl)imidazolidin-2-one (dimethylolethyleneurea),-   1,3-bis(hydroxymethyl)-1,3-hexahydropyrimidin-2-one    (dimethylolpropyleneurea),-   1,3-bis(methoxymethyl)-4,5-dihydroxyimidazolidin-2-one (DMeDHEU) and-   tetra(hydroxymethyl)acetylenediurea.

In a preferred embodiment of the invention, the crosslinkable ureacompound is selected from1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one and a1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one modified with aC₁-C₆-alkanol, a C₂-C₆-polyol or an oligoethylene glycol.

mDMDHEU are reaction products of1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one with aC₁-C₆-alkanol, a C₂-C₆-polyol, an oligoethylene glycol or mixtures ofthese alcohols. Suitable C₁₋₆-alkanols are, for example, methanol,ethanol, n-propanol, isopropanol, n-butanol and n-pentanol, methanolbeing preferred. Suitable polyols are ethylene glycol, diethyleneglycol, 1,2- and 1,3-propylene glycol, 1,2-, 1,3- and 1,4-butyleneglycol and glycerol. Suitable oligoethylene glycols are in particularthose of the formula HO(CH₂CH₂O)_(n)H, where n is from 2 to 20, amongwhich diethylene glycol and triethylene glycol are preferred. For thepreparation of mDMDHEU, DMDHEU are mixed with the alkanol, the polyol orthe polyethylene glycol. Here, the monohydric alcohol, the polyol oroligo- or polyethylene glycol is usually used in a ratio of from 0.1 to2.0, in particular from 0.2 to 2, mole equivalents each, based onDMDHEU. The mixture of DMDHEU and the polyol or the polyethylene glycolis usually reacted in water at temperatures of, preferably, from 20 to70° C. and a pH of, preferably, from 1 to 2.5, the pH being adjusted asa rule to a range of from 4 to 8 after the reaction.

In addition to the urea compounds H or the reaction products orprecondensates thereof (component A), the curable aqueous compositionsmay also comprise one or more of the abovementioned alcohols,C₁-C₆-alkanols, C₂-C₆-polyols, oligoethylene glycols or mixtures ofthese alcohols (component C). Suitable C₁₋₆-alkanols are, for example,methanol, ethanol, n-propanol, isopropanol, n-butanol and n-pentanol,methanol being preferred. Suitable polyols are ethylene glycol,diethylene glycol, 1,2- and 1,3-propylene glycol, 1,2-, 1,3- and1,4-butylene glycol and glycerol. Suitable oligoethylene glycols are inparticular those of the formula HO(CH₂CH₂O)_(n)H, where n is from 2 to20, among which diethylene glycol and triethylene glycol are preferred.

The concentration of urea compound H or the reaction product orprecondensate thereof in the aqueous composition is usually in the rangefrom 1 to 60% by weight, frequently in the range from 10 to 60% byweight and in particular in the range from 15 to 50% by weight, based onthe total weight of the composition. If the curable, aqueous compositioncomprises one of the abovementioned alcohols, the concentration thereofis preferably in the range from 1 to 50% by weight, in particular in therange from 5 to 40% by weight. The total amount of component A) andcomponent C) usually accounts for from 10 to 60% by weight and inparticular from 20 to 50% by weight of the total weight of the aqueouscomposition.

In addition to the components A) and, if appropriate, C), the aqueouscomposition may also comprise a catalyst K which effects crosslinking ofthe urea compound H or of its reaction product or precondensate. As arule, metal salts from the group consisting of the metal halides, metalsulfates, metal nitrates, metal phosphates and metal tetrafluoroborates;boron trifluoride, ammonium salts from the group consisting of theammonium halides, ammonium sulfate, ammonium oxalate and diammoniumphosphate; and organic carboxylic acids, organic sulfonic acids, boricacid, sulfuric acid and hydrochloric acid are suitable as catalyst K.

Examples of metal salts suitable as catalysts K are in particularmagnesium chloride, magnesium sulfate, zinc chloride, lithium chloride,lithium bromide, aluminum chloride, aluminum sulfate, zinc nitrate andsodium tetrafluoroborate.

Examples of ammonium salts suitable as catalysts K are in particularammonium chloride, ammonium sulfate, ammonium oxalate and diammoniumphosphate.

Water-soluble organic carboxylic acids, such as maleic acid, formicacid, citric acid, tartaric acid and oxalic acid, and furthermorebenzenesulfonic acid and p-toluene-sulfonic acid, but also inorganicacids, such as hydrochloric acid, sulfuric acid, boric acid or mixturesthereof, are in particular also suitable as catalysts K.

The catalyst K is preferably chosen from magnesium chloride, zincchloride, magnesium sulfate, aluminum sulfate and mixtures thereof,magnesium chloride being particularly preferred.

The catalyst K is usually added to the aqueous composition only shortlybefore the impregnation of the lignocellulose material. It is usuallyused in an amount of from 1 to 20% by weight, in particular from 2 to10% by weight, based on the total weight of the components A) and, ifappropriate, C) present in the curable, aqueous composition. Theconcentration of the catalyst is usually in the range from 0.1 to 10% byweight and in particular in the range from 0.5 to 5% by weight, based onthe total weight of the curable, aqueous composition.

Furthermore, the aqueous composition used for the impregnation maycomprise a part or the total amount of the binders which are requiredfor the production of the moldings and which are explained in moredetail further below. If desired, the concentration of the binder in theaqueous composition is usually in the range from 0.5 to 25% by weight,frequently in the range from 1 to 20% by weight and in particular in therange from 5 to 15% by weight, based on the total weight of the aqueouscomposition and calculated as dry glue components (i.e. without anysolvent or diluent components of the binder).

It is assumed that the binder components of the glue composition, incontrast to crosslinkable urea compounds, the catalyst K and anyalcohols of component C) which are present are not absorbed or areabsorbed only to a small extent by the cell walls of the lignocelluloseparticles and remain substantially on the surface of the particles andthey are therefore available as binder in the subsequent shaping processof the production of the moldings.

The preparation of the finely divided materials impregnated with theaqueous composition and based on lignocellulose can in principle beeffected by two different methods.

Thus, according to a first embodiment of the invention, acoarse-particled, untreated material based on lignocellulose, e.g. woodblocks, can be treated with the aqueous compositions which comprise acatalyst K in the manner described in WO 2004/033170 or WO 2004/033171and then comminuted, for example by conversion into chips, defibering ormilling, or the treated wood chips or wood fibers obtained on processingor recycling of the materials thus obtained can be recovered.

Preferably, however, an untreated, finely divided material based onlignocellulose is impregnated with the curable aqueous composition andthe catalyst K and then exposed to conditions which effect crosslinkingof the urea compounds present in the composition and hence curing of thecomposition. The aqueous composition and the catalyst K can be appliedtogether in one composition or in two separate compositions to theuntreated finely divided material based on lignocellulose. Usually,however, the catalyst K is incorporated into the aqueous compositionbefore the application. However, it is also conceivable to impregnatethe finely divided material based on lignocellulose simultaneously or insuccession with a first aqueous formulation which comprises the catalystK in dissolved form, and a second aqueous composition which comprisesthe crosslinkable urea compound and, if appropriate, the alcoholcomponent C).

The type of untreated finely divided lignocellulose material depends ina known manner on the molding to be produced. Examples of suitablefinely divided lignocellulose materials comprise, without beingrestricted thereto, finely divided materials comprising wood, such as,for example, wood chips, for example from chipped round wood and logs,chipped industrial wood and residual industrial wood, sawmill and veneerwastes, chips from thermomechanically digested wood, shavings fromplaning and peeling, wood chips and wood shreds, and furthermorelignocellulose-containing raw materials differing from wood, such asbamboo, bagasse, cotton stalks, jute, sisal, straw, flax, coconutfibers, banana fibers, reeds, e.g. Chinese silvergrass, ramie, hemp,Manila hemp, esparto (alfa grass), rice husks and cork.

The untreated finely divided lignocellulose materials may be present inthe form of granules, powder or preferably chips, including sawdust andplaning shavings, fibers and/or shreds. Among these, materialscomprising wood and bamboo, such as wood fibers, wood chips and woodshreds or bamboo fibers, bamboo shreds and bamboo chips and mixturesthereof, are particularly preferred. These are in particular finelydivided materials comprising wood. The wood species of which the finelydivided materials consist comprise, for example, softwood, such asdouglas fir, spruce, pine, larch, stone pine, fir, cedar and Swiss stonepine, and hardwood, such as maple, acacia, birch, beech, oak, alder,ash, aspen, hazel, hornbeam, cherry, lime, poplar, locust, elm, walnut,willow, adriatic oak and the like.

The dimensions, i.e. the measurements (length, thickness), which atleast 90% of the finely divided lignocellulose materials have is usuallyin the range from 0.1 to 20 mm, in particular from 0.5 to 10 mm, andespecially from 1 to 5 mm, it being possible for the length which atleast 90% of the particles have also to exceed 10 mm and be up to 200 mmin the case of elongated finely divided materials having a length/widthratio>5. The average width or thickness of elongated particles istypically in the range from 0.1 to 10, in particular in the range from0.2 to 5, mm and especially in the range from 0.3 to 3 mm.

The impregnation or soaking, respectively, of the untreated finelydivided materials based on lignocellulose can be carried out, forexample, by immersing the fibers in the aqueous composition, by applyingreduced pressure, if appropriate in combination with pressure, or byspraying. The conditions are as a rule chosen so that the amount ofcurable components of the aqueous composition which are absorbed is atleast 1% by weight, based on the dry matter of the untreated material.The amount of curable components which is absorbed may be up to 100% byweight, based on the dry matter of the untreated lignocellulosematerials and is frequently in the range from 1 to 60% by weight,preferably in the range from 5 to 50% by weight and in particular in therange from 10 to 30% by weight, based on the dry matter of the untreatedmaterial used. Usually, the impregnation is effected at ambienttemperature, typically in the range from 15 to 40° C.

The moisture of the untreated lignocellulose materials used for theimpregnation is not critical and may be, for example, up to 100% byweight. Here and below, the term “moisture” is synonymous with the termresidual moisture content according to DIN 52183. Frequently, it is inthe range from 1 to 80% and in particular from 5 to 50%.

On immersion, the untreated finely divided lignocellulose materials,which advantageously have a moisture content in the range from 1% to100%, are immersed for a period of from a few seconds to 12 h, inparticular from 1 min to 60 min, in the aqueous composition in acontainer or are suspended therein. The finely divided lignocellulosematerial absorbs the aqueous impregnating composition during this, itbeing possible for the amount of curable components which is absorbed bythe finely divided lignocellulose material to be controlled by theconcentration of curable components (i.e. components A) and C)) in theaqueous composition, by the temperature and by the duration oftreatment. The amount of curable components which is actually absorbedcan be determined by the person skilled in the art in a simple mannerfrom the weight increase of the finely divided lignocellulose materialand the concentration of the aqueous composition.

The impregnation can also be achieved by applying reduced pressure, itbeing possible, if appropriate, for a phase of elevated pressure tofollow. For this purpose, the finely divided lignocellulose material isbrought into contact with the aqueous composition under reducedpressure, which is frequently in the range from 10 to 500 mbar and inparticular in the range from 50 to 100 mbar, for example by immersion orsuspension in the curable aqueous composition. The time span is usuallyin the range from 1 min to 1 h. If appropriate, a phase at elevatedpressure, for example in the range from 1 bar to 20 bar, follows. Theduration of this phase is usually in the range from 1 min to 6 h, inparticular from 5 min to 1 h. During this, the finely dividedlignocellulose material absorbs the aqueous impregnating composition, itbeing possible for the amount of curable components which is absorbed bythe finely divided lignocellulose material to be controlled by theconcentration of curable components in the aqueous composition, by thepressure applied, by the temperature and by the duration of treatment.Here too, the amount actually absorbed can be calculated from the weightincrease of the finely divided lignocellulose material.

In a further embodiment of the invention, the impregnation is effectedby spraying the untreated lignocellulose particles with the aqueouscomposition. The lignocellulose particles advantageously have a moisturecontent of not more than 50%, for example in the range from 1% to 30%.The spraying is usually effected at temperatures in the range from 15 to50° C. The amount of curable components which is absorbed by the finelydivided lignocellulose material can be controlled by the concentrationof curable components in the aqueous composition, by the amount applied,by the temperature and by the duration of spraying. The amount ofcurable components which is actually absorbed results directly from theamount of aqueous composition sprayed on. The spraying can be carriedout in a conventional manner in all apparatuses suitable for thespraying of solids, for example in spray towers, fluidized-bedapparatuses and the like.

The impregnation can also be effected by means of ultrasound.

The impregnated finely divided lignocellulose particles thus obtainedare further processed to give moldings, if appropriate after a dryingstep and/or a curing step.

In many cases, the further processing comprises glue-coating of thetreated finely divided material with a liquid or pulverulent formulationof a binder and shaping and curing of the treated material to give amolding. In other cases, for example in the production of WPCs, thefurther processing comprises mixing of the material obtained in step i)with a thermoplastic polymer and shaping of the mixture. In this case,the production in step i) usually comprises an impregnation and a dryingor curing step.

The invention therefore also relates to a process for the production ofmoldings from finely divided lignocellulose-based materials, comprising

-   i) provision of a lignocellulose-based finely divided material which    is impregnated with the curable, aqueous composition described here    and is, if appropriate, cured,-   ii) glue-coating of the finely divided lignocellulose-based material    obtained in step i) or a mixture thereof with other finely divided    materials with a liquid or pulverulent formulation of a binder; and-   iii) shaping and curing of the glue-coated finely divided material    to give a molding,    or-   ii′) mixing of the treated, preferably dried and/or cured finely    divided lignocellulose-based material obtained in step i) with a    thermoplastic polymer and-   iii′) shaping of the mixture to give a molding.

The invention also relates to the moldings obtainable by the process.

If the provision of the treated finely divided lignocellulose materialscomprises the impregnation of untreated lignocellulose materials, adrying step, also predrying step below, can be carried out after theimpregnation in step i) and before the glue-coating in step ii). Duringthis, the volatile components of the aqueous composition, in particularthe water and excess organic solvents which do not react in thecuring/crosslinking of the urea compounds, are partly or completelyremoved. In addition, depending on the chosen drying temperature,partial or complete curing/crosslinking of the curable componentspresent in the formulation may take place. The predrying/curing of theimpregnated materials is usually effected at temperatures of from 50° C.to 220° C., in particular in the range from 80 to 200° C. If curing isdesired, the drying is preferably effected at above 100° C. Thecuring/drying can be carried out in a conventional fresh air/exhaust airsystem, for example a drum drier. The predrying is preferably effectedin a manner such that the moisture content of the finely dividedlignocellulose materials after the predrying is not more than 30%, inparticular not more than 20%, based on the dry matter. It may beadvantageous to carry out the drying/curing to a moisture content of<10% and in particular <5%, based on the dry matter. The moisturecontent can be controlled in a simple manner by the temperature, theduration and the pressure chosen in the predrying.

However, a predrying step is in principle not necessary, and removal ofvolatile components and crosslinking of the curable components of theaqueous composition can also be effected after the glue-coating in stepii) or can be carried out in the shaping and curing step iii). Such aprocedure not only has the advantage of simplifying the process butpermits shorter glue-coating and shaping times. In a preferredembodiment, therefore, preferably no separate drying step is carried outand the glue-coating is effected immediately after the impregnation orsimultaneously therewith.

If the aqueous composition already comprises an amount of binder whichis sufficient for the production of the molding, treatment step i) andglue-coating ii) take place at the same time, and the removal of thevolatile components and the crosslinking of the curable components ofthe aqueous composition are carried out in the shaping and curing stepiii).

If the aqueous composition used for the impregnation in step i) does notcomprise an amount of binder which is sufficient for the production ofthe moldings, the impregnated and, if appropriate, predried and curedlignocellulose particles are then glue-coated in a conventional mannerwith the binder required for the production of the moldings.

The glue-coating can be effected in a conventional manner. Ifappropriate, further finely divided materials forming the molding,additives, catalysts or assistants are added at this stage.

The type of binder depends in a known manner on the type of molding tobe produced. Suitable binders are described, for example, in A. Pizzi(editor): Wood Adhesives, Marcel Dekker, New York 1983. Examples ofbinders are:

-   i) heat-curable binders (reactive binders), such as aminoplast    resins, phenol resins, isocyanate resins, epoxy resins and    polycarboxylic acid resins;-   ii) thermoplastic materials, such as polyethylene, polypropylene,    polystyrene resins, polysulfones and polyester resins; and-   iii) film-forming polymers, for example aqueous polymer dispersions    based on styrene-acrylates, polyacrylates (acrylic ester/methacrylic    ester copolymers), vinyl acetate polymers (polyvinyl acetate),    styrene-butadiene copolymers and the like.

Preferred binders are the heat-curable binders mentioned in group i) andmixtures thereof with film-forming polymers of group iii), theheat-curable binders preferably being used in the form of aqueousformulations.

Preferred binders are aminoplast resins, phenol resins, isocyanateresins, polyvinyl acetate and polycarboxylic acid resins.

Particularly suitable aminoplast resins are formaldehyde condensates ofurea (urea-formaldehyde condensates) and of melamine(melamine-formaldehyde condensates). They are commercially available asaqueous solutions or powders with the names Kaurit® and Kauramin®(produced by BASF) and comprise urea- and/or melamine-formaldehydeprecondensates. Typical phenol resins are phenol-formaldehydecondensates, phenol-resorcinol-formaldehyde condensates and the like.Cocondensates of aminoplast resins and phenol resins are also suitable.Examples of cocondensates of aminoplast resins and phenol resins areurea-melamine-formaldehyde condensates,melamine-urea-formaldehyde-phenol condensates and their mixtures. Theirpreparation and use for the production of moldings from finely dividedlignocellulose materials are generally known. Urea-formaldehyde resinsare preferred, and among these in particular those having a molar ratioof 1 mol of urea to 1.1 to 1.4 mol of formaldehyde.

In the processing of aminoplast resins and phenol resins, there is atransition from the soluble and fusible precondensates to infusible andinsoluble products. In this process designated as curing, completecrosslinking of the precondensates is known to occur, which as a rule isaccelerated by curing agents. Curing agents which may be used are thecuring agents known to the person skilled in the art for urea-, phenol-and/or melamine-formaldehyde resins, such as acidic and/oracid-eliminating compounds, e.g. ammonium or amine salts. As a rule, theproportion of curing agent in an adhesive resin liquor is from 1 to 5%by weight, based on the proportion of liquid resin.

Suitable isocyanate resins are all conventional resins based onmethylenediphenylene isocyanates (MDI). As a rule, they consist of amixture of monomers and oligomeric di- or polyisocyanates, the so-calledprecondensates, which are capable of reacting with the cellulose, thelignin and the moisture content of the lignocellulose particles.Suitable isocyanate resins are commercially available, for example, asLupranate brands (Elastogran).

Examples of reactive polycarboxylic acid resins are compositionscomprising

-   i) a polymer P of ethylenically unsaturated monomers which is    composed of from 5 to 100, preferably from 5 to 50, % by weight of    an ethylenically unsaturated acid anhydride or of an ethylenically    unsaturated dicarboxylic acid whose carboxyl groups can form an    anhydride, or the reaction products thereof with alkanolamines    (monomers a)), and from 0 to 95% by weight, preferably from 50 to    95% by weight, of monomers b) which differ from the monomers a); and-   ii) at least one alkanolamine A-(OH)₂ having at least two hydroxyl    groups and/or an alkoxylated polyamine and-   iii) if appropriate, a water-insoluble, water-dispersible    film-forming polymer P′.

Reactive polycarboxylic acid resins are known to the person skilled inthe art and are described in, for example, EP-A-882 093, WO 97/45461, WO99/09100, WO 99/02591, WO 01/27163 and WO 01/27198.

Polymers P which comprise maleic acid and/or maleic anhydride asmonomers a) are particularly preferred.

Preferred monomers b) are ethylenically unsaturated C₃-C₆-monocarboxylicacids, such as acrylic acid or methacrylic acid, olefins, such asethene, propene, butene, isobutene, cyclopentene or diisobutene,vinylaromatics, such as styrene, alkyl vinyl ethers, e.g. methyl vinylether or ethyl vinyl ether, acrylamide,2-acrylamido-2-methylpropanesulfonic acid, vinyl acetate, butadiene,acrylonitrile or mixtures thereof. Particularly preferred monomers b)are acrylic acid, methacrylic acid, ethene, acrylamide, styrene andacrylonitrile or mixtures thereof.

Polymers P in which the monomer b) comprises at least oneC₃-C₆-monocarboxylic acid, preferably acrylic acid, as comonomer b) areparticularly preferred.

Alkanolamines having at least two OH groups, such as diethanolamine,triethanolamine, diisopropanolamine, triisopropanolamine,methyldiethanolamine, butyldiethanolamine and methyldiisopropanolamine,are mentioned as component A-(OH)₂. Triethanolamine is preferred.Component A-(OH)₂ furthermore includes alkoxylated, in particularethoxylated, polyamines, as described in WO 97/45461, for examplecompounds of the formulae I and in particular Ia, Ie and If describedthere.

All water-insoluble polymers which are film-forming and are dispersiblein water are in principle suitable as component P′ and as a binder ofgroup iii). These include in particular emulsion polymers and thepowders prepared therefrom, such as those referred to as polymers A1,for example, in WO 01/27198. The polymers P′ frequently have a glasstransition temperature in the range from −10 to +150° C. and inparticular in the range from +20 to +120° C. They are in particularcopolymers based on styrene/butadiene, based on styrene/alkyl acrylateand those based on alkyl methacrylate/alkyl acrylate.

For the preparation of the polycarboxylic acid resins, the polymer P andthe alkanolamine A-(OH)₂ are preferably used in a ratio relative to oneanother such that the molar ratio of carboxyl groups of the component Pand of the hydroxyl groups of the component A-(OH)₂ is from 20:1 to 1:1,preferably from 8:1 to 5:1 and particularly preferably from 5:1 to 1.7:1(the anhydride groups are calculated here as 2 carboxyl groups).

The binder is usually used in amounts of from 0.5 to 30% by weight,frequently from 1 to 20% by weight, in particular in amounts from 5 to15% by weight, based on the treated lignocellulose materials.

Preferred binders of group i) can of course also be used as mixtureswith one another or as mixtures with binders of groups ii) and inparticular iii).

In addition, conventional assistants and additives can be used for theproduction of the moldings, such as the abovementioned curing agents,i.e. catalysts, which result in more rapid crosslinking of the binder.

The assistants include, for example, bactericides or fungicides andwater repellents for increasing the water resistance of the moldings.Suitable water repellents are conventional aqueous paraffin dispersionsor silicones. Furthermore, wetting agents, thickeners, plasticizingagents and retention aids can be used in the production. These arefrequently added to the binder composition. The binder compositionsfrequently also comprise coupling reagents, such as alkoxysilanes, forexample 3-aminopropyltriethoxysilane, soluble or emulsifiable oils aslubricants and dust-binding agents and wetting assistants.

Conventional additives comprise inert fillers, such as aluminumsilicates, quartz, precipitated or pyrogenic silica, gypsum and barytes,talc, dolomite or calcium carbonate; color-imparting pigments, such astitanium white, zinc white, iron oxide black, etc.

Finally, conventional fireproofing agents, such as, for example,aluminum silicates, aluminum hydroxides, borates and/or phosphates, canbe used in the production of the moldings.

The glue-coating is effected by the methods customary for this purpose,for example by mixing the finely divided, impregnated lignocellulosematerials with the binder in conventional mixing apparatuses for mixingliquid with solid materials, by fluidizing the lignocellulose materialsin an air stream and spraying the binder, preferably in the form of aliquid binder composition, into the fiber stream thus produced(“blow-line” method).

The glue-coated mixture of lignocellulose-containing materials and thebinder composition can be predried at elevated temperature, for exampleat temperatures of from 10 to 200° C., for removal of volatilecomponents prior to shaping. Depending on the type of bindercomposition, however, the removal of volatile components can also bedispensed with or can be carried out during the shaping step.

After the glue-coating and, if appropriate, predrying, a shaping step iseffected, which is carried out in a manner known per se, as a rule atelevated temperature, for example at temperatures of from 50 to 300° C.,preferably from 100 to 250° C. and particularly preferably from 140 to225° C., and usually at elevated pressures of, in general, from 2 to 200bar, preferably from 5 to 100 bar, particularly preferably from 20 to 50bar.

Suitable methods of shaping are familiar to the person skilled in theart and comprise, for example, extrusion methods, thermoforming and inparticular hot pressing, it being possible for these methods to bebatchwise or continuous, for example as roller pressing, gliding filmpressing, calender pressing, extrusion pressing or steam injectionpressing. An overview of conventional methods is to be found, forexample, in Ullmann's Encyclopedia of Industrial Chemistry, “Wood—Woodbased Materials”, Sections 2.3.1, 2.3.2 and 2.3.3, 5th Edition onCD-ROM, Wiley-Verlag-Chemie, Weinheim 1997.

At the temperatures prevailing during the shaping and the pressure,adhesion of the lignocellulose particles and, depending on the type ofbinder, melting and/or crosslinking of the binder components takes placeso that a stable molding forms on cooling and removal of the mold.

The moldings may be shaped in any desired manner and comprise sheet-likemoldings, such as boards or mats, or have a 3-dimensional form, forexample specially shaped articles. Examples of sheet-like moldingscomprise OSB boards (oriented structural board), particle boards, waferboards, insulating panels, medium density fiberboards (MDF) and highdensity fiberboards (HDF). The moldings according to the invention alsoinclude OSL boards and OSL shaped articles (oriented strand lumber) andPSL boards and PSL shaped articles (parallel strand lumber). Themoldings also include shaped articles comprising WPC (wood-plasticcomposites).

The process according to the invention is particularly suitable for theproduction of moldings wherein the lignocellulose material is wood.Here, depending on the size of the lignocellulose-containing particlesused, a distinction is made between OSB boards (oriented structuralboards), particle boards, wafer boards, OSL boards and OSL shapedarticles (oriented strand lumber), PSL boards and PSL shaped articles(parallel strand lumber), insulating panels and medium densityfiberboards (MDF) and high density fiberboards (HDF) and the like.

The process according to the invention is also particularly suitable forthe production of so-called WPC (wood-plastic composites), as described,for example, in WO 96/34045, and the literature cited there and in ageneral manner in Öster. Kunststoffzeitschrift 35, 2004, 10-13 and inKlauditzforum 5th Edition 6/2004. The processes known for the productionof WPC can be carried out in an analogous manner with the lignocellulosematerials treated according to the invention.

For the production of the WPCs, the finely divided lignocellulosematerial treated according to the invention, after a drying/curing stephas been carried out beforehand, is mixed with at least onethermoplastic material, for example thermoplastic polymers based onpoly-C₂-C₆-olefins, such as polyethylene, polypropylene and the like, orbased on poly-C₂-C₄-haloolefins, such as polyvinyl chloride,polyvinylidene chloride or copolymers of vinyl chloride with vinylidenechloride, vinyl acetate and/or C₂-C₆-olefins, and then subjected to ashaping process, as a rule an injection molding or extrusion process.The amount of thermoplastic polymer generally accounts for from 20 to90% by weight and in particular from 30 to 80% by weight, based on thetotal mass. Accordingly, the proportion of finely divided lignocellulosematerial treated according to the invention is in the range from 10 to80% by weight and in particular from 20 to 70% by weight, based on thetotal weight of the WPC. In addition, conventional additives, such asadhesion promoters (e.g. organosilanes, maleic anhydride, isocyanates),pigments, light stabilizers, lubricants or fire-retardant components,can be added to the WPCs. The addition of biocides is on the other handnot required.

The finely divided lignocellulose materials treated according to theinvention are particularly suitable for the production of wood-basematerials, such as wood particle boards and wood fiberboards, includingHDF, MDF, OSB, OSL and PSL (cf. Ullmann's Encyclopedia of IndustrialChemistry, loc. cit.), which are produced by gluing of comminuted wood,such as, for example, wood chips, wood shreds and/or wood fibers.

The production of particle boards is generally known and is described,for example, in H. J. Deppe, K. Ernst Taschenbuch derSpanplattentechnik, 2nd Edition, Verlag Leinfelden 1982, and can be usedanalogously in the process according to the invention.

In the production of particle board, the glue-coating of the previouslydried chips is effected in continuous mixers. In general, different chipfractions are differently glue-coated in separate mixers and then pouredseparately (multilayer boards) or together. Chips whose average chipthickness is from 0.1 to 2 mm, in particular from 0.2 to 0.5 mm, andwhich comprise less than 6% by weight of water are preferably used. Thebinder composition is applied as uniformly as possible to the woodchips, for example by spraying the binder composition in finely dividedform onto the chips. The glue-coated wood chips are then scattered toform a layer having a surface which is as uniform as possible, thethickness of the layer depending on the desired thickness of the finalparticle board. The scattered layer is, if appropriate, precompressedwhile cold and pressed to give a dimensionally accurate board at atemperature of, for example, from 100 to 250° C., preferably from 140 to225° C. by application of pressures of, usually, from 10 to 750 bar. Therequired pressing times may vary within a wide range and are in generalfrom 15 second to 30 minutes.

The wood fibers of suitable quality which are required for theproduction of medium density wood fiberboards (MDF) can be produced frombark-free wood shreds by grinding in special mills or so-called refinersat temperatures of about 180° C. In the case of MDF and HDF boardproduction, the fibers are glue-coated in the blow-line after therefiner. For glue-coating, the wood fibers are generally fluidized in anair stream, and the binder composition is sprayed into the fiber streamthus produced (“blow-line” method). The glue-coated fibers then passthrough a drier in which they are dried to moisture contents of from 1to 20% by weight. In a few cases, the fibers are also first dried andsubsequently glue-coated in special continuous mixers. A combination ofblow-line and mixer glue-coating is also possible. The ratio of woodfibers to binder composition, based on the dry content or solidscontent, is usually from 40:1 to 3:1, preferably from 20:1 to 4:1. Theglue-coated fibers are dried in the fiber stream at temperatures, of,for example, from 130 to 180° C., scattered to give a fiber mat, ifappropriate precompressed while cold and compressed at pressures of from20 to 40 bar to give boards or moldings.

In the case of OSB production, the wood chips (strands), if appropriateafter drying, are separated into middle and outer layer material andglue-coated separately in continuous mixers. For completion of theboards, the glue-coated wood chips are then poured to give mats, ifappropriate precompressed while cold and pressed with heated presses attemperatures of from 170 to 240° C. to give boards.

The glue-coated wood fibers can also be processed to give atransportable fiber mat, as described, for example, in DE-A 2 417 243.This semifinished product can then be further processed in a secondspatially separate step carried out at a different time to give boardsor shaped articles, such as, for example, interior trims of doors ofmotor vehicles.

Other lignocellulose materials, for example natural fibers, such assisal, jute, hemp, ramie, straw, flax, coconut fibers, banana fibers andother natural fibers, can also be processed with the use of bindersknown per se to give boards and moldings. The natural fibers can also beused as mixtures with plastics fibers, for example polypropylene,polyethylene, polyester, polyamides or polyacrylonitrile. These plasticsfibers may also act as cobinders in addition to the abovementionedbinder composition. The proportion of the plastics fibers is preferablyless than 50% by weight, in particular less than 30% by weight and veryparticularly preferably less than 10% by weight, based on all chips,shreds or fibers. The processing of the fibers can be effected bymethods practiced in the case of the wood fiberboards. However,preformed natural fiber mats can also be impregnated with the bindersaccording to the invention, if appropriate with addition of a wettingassistant. The impregnated mats are then pressed in the binder-moist orpredried state, for example at temperatures of from 100 to 250° C. andpressures of from 10 to 100 bar, to give boards or shaped articles.

Owing to their high stability, the moldings according to the inventionare suitable for a multiplicity of different applications, in particularfor applications in which they are exposed to weathering and moisture,for example as a base for structural components in house building and inshipbuilding, for example for interior and exterior walls, floorconstruction, for the production of claddings in house building,shipbuilding and automotive construction, for example as exterior trims,interior trims, trunk and engine space linings, as a substrate fordecorative panels, such as ceiling, wall and prefabricted parquetpanels, as components and boards in the furniture industry and for thedo-it-yourself sector, etc.

The following examples are intended merely to explain the examplesaccording to the invention and are not to be understood as beinglimiting.

The stated moisture contents were determined according to DIN 52183.

EXAMPLE 1

The impregnating agent used was a 50% strength aqueous solution of aDMDHEU modified with diethylene glycol and methanol (mDMDHEU), whichsolution was mixed with 1.5% of MgCl₂.6H₂O.

Thermomechanically digested spruce wood chips having an average fiberlength (90% value) and a moisture content of 11% were introduced into animpregnating unit by means of a metal basket. The impregnating unit wassubjected to a reduced pressure of 100 mbar absolute for 30 minutes andthen flooded with the impregnating agent. A pressure of 10 bar was thenapplied for one hour. The pressure phase was terminated and the residualliquid was removed. The chips thus obtained were then dried in a drierfor 4 h at 50° C.

EXAMPLE 2

In a manner analogous to example 1, planing shavings of pinewood havingaverage dimensions of 0.5 mm×5 mm×100 mm were impregnated and thendried.

EXAMPLE 3

The impregnated pinewood shavings obtained in example 2 were heated to130° C. in a drying oven for 1 h, cured pinewood shavings beingobtained.

EXAMPLE 4 Production of a Particle Board

5400 g of dried chips from example 1 were sprayed with 1628 g of thecomposition stated in table 1, and 3370 g thereof were poured into amold (56.5 cm×44 cm). The material was pressed in a press at 190° C. upto a thickness of 18 mm in 230 s to give a particle board.

The particle board comprised 14% of solid resin/absolutely dry chips,0.5% of solid wax/absolutely dry chips (absolutely dry=% by weight,based on dry chips).

TABLE 1 Urea-formaldehyde resin, 68% strength 100.0 p  Paraffinemulsion, 60% strength 6.3 p Ammonium nitrate solution, 52% strength 4.0p p = parts by weight

EXAMPLE 5 Production of an MDF Board

1000 g of absolutely dry fibers from example 3 were sprayed with theglue batch stated in table 2 and dried to a moisture content of 8%. 920g thereof were poured into a mold (30 cm×30 cm). The material waspressed in a press at 190° C. to a thickness of 12 mm in 300 s to givean MDF board.

The MDF board comprised 14% of solid resin/absolutely dry fibers and0.5% of solid wax/absolutely dry fibers.

TABLE 2 Urea-formaldehyde resin, 68% strength 100.0 g  Paraffinemulsion, 60% strength 3.2 g Water 11.8 g 

EXAMPLE 6

In each case 70 g of wood fibers from example 3 were thoroughly mixedwith 13.2 g of a pulveruient composition according to example P2 to P6of WO 01/27198.14 g of water were then also sprayed onto thisfiber-binder mixture with continued mixing. The glue-coated fibers weredried at 70° C. to a residual moisture content of 10% (absolutely dry)and scattered to give a 19×19 cm fiber mat.

These fiber mats were compressed using a hydraulic press (manufacturerWickert Maschinenbau GmbH, Landau, model WKP 600/3.5/3) at a pressingtemperature of 220° C. for 120 sec between two metal plates with 2 mmspacers. For this purpose, a press pressure of 50 bar was firstestablished. After the pressure had been relieved for 10 sec, a pressureof 200 bar was then maintained for a further 90 sec.

The fiberboards obtained were stored for 24 h under standard temperatureand humidity conditions at 23° C. and 65% relative humidity and thentested. The water absorption was determined from the weight increase (in%, based on the original weight). The swelling, based on thickness, ofthe wood fiberboards was determined as a relative increase in thethickness of 2×2 cm test specimens after storage for 24 h indemineralized water analogously to DIN 52351.

EXAMPLE 7

Shavings, prepared by chipping pine panels modified with DMDHEU,prepared according to WO 2004/033170, by analogy to example 2, werepressed with the glues given in Table 3 by analogy to example 4 at 190°C. for 230 s to give particle boards (density 650 kg/m³). Likewise,non-modified pinewood shavings were pressed under similar conditions togive particle boards. The thus prepared particle boards were stored indemineralised water at ambient temperature for 24 h and the swelling wasdetermined as a relative increase in the thickness.

TABLE 7 Swelling after 24 h Shavings [%] Kaurit ® 418¹⁾ [% b.w.]²⁾ 8non-modified 25.7 10  non-modified 19.5 8 modified 14.1 10  modified10.5 Kauramin ® 620³⁾ [% b.w]²⁾ 8 non-modified 20.4 10  non-modified16.3 8 modified 11.9 10  modified 9.1 Kaurit ® 347⁴⁾ [% b.w.]²⁾⁾ 6non-modified 35.9 8 non-modified 22.1 6 modified 19.5 8 modified 15.4Kaurit ® 350⁵⁾ [% b.w.]²⁾⁾ 6 non-modified 29.4 8 non-modified 22.3 6modified 19.5 8 modified 15.4 ^(1),4),5))aqueous urea resin glues,brands of BASF AG, Ludwigshafen ²⁾resin components, based on shavings(absolute dry) ³⁾aqueous melamine resin glue, brand of BASF AG,Ludwigshafen

1. (canceled)
 2. The process according to claim 9, wherein thecrosslinkable urea compound is selected from1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one,1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one which is modifiedwith a C₁-C₆-alkanol, a C₂-C₆-polyol or an oligo- or a polyethyleneglycol, 1,3-bis(hydroxymethyl)urea, 1,3-bis(methoxymethyl)urea;-1-hydroxymethyl-3-methylurea, 1,3-bis(hydroxymethyl)imidazolidin-2-one,1,3-bis(hydroxymethyl)-1,3-hexahydropyrimidin-2-one,1,3-bis(methoxymethyl)-4,5-dihydroxyimidazolidin-2-one,tetra(hydroxymethyl)acetylenediurea.
 3. The process according to claim9, wherein the crosslinkable urea compound is1,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one or a1,3-bis(hydroxymethyl-4,5-dihydroxyimidazolidin-2-one modified with aC₁-C₆-alkanol, a C₂-C₆-polyol or an oligo- or a polyethylene glycol.4-5. (canceled)
 6. The process according to claim 9, wherein thecatalyst K is selected from metal salts from the group consisting of themetal halides, metal sulfates, metal nitrates, metal phosphates, metaltetrafluoroborates; boron trifluoride; ammonium salts from the groupconsisting of the ammonium halides, ammonium sulfate, ammonium oxalateand diammonium phosphate; organic carboxylic acids, organic sulfonicacids, boric acid, sulfuric acid and hydrochloric acid.
 7. The processaccording to claim 9, wherein the catalyst K is magnesium chloride. 8.The process according to claim 9, wherein the concentration of thecatalyst in the aqueous composition is in the range from 0.1 to 20% byweight, based on the total weight of the composition.
 9. A process forthe production of moldings from finely divided materials based onlignocellulose, comprising i) provision of a finely divided materialbased on lignocellulose and treated with a curable, aqueous composition,the curable aqueous composition comprising: a) at least onecrosslinkable urea compound from the group consisting of the ureacompounds H which have at least one N-bonded group of the formula CH₂OR,where R is hydrogen or C₁-C₄-alkyl, and/or a1,2-bishydroxyethane-1,2-diyl group bridging the two nitrogen atoms ofthe urea, precondensates of the urea compound H, and reaction productsor mixtures of the urea compound H with at least one alcohol which isselected from C₁-C₆-alkanols, C₂-C₆-polyols and oligoethylene glycols,and b) at least one catalyst K effecting crosslinking of the ureacompound; ii) glue-coating of the finely divided material based onlignocellulose and obtained in step i) or of a mixture thereof withother finely divided materials with a liquid or pulverulent formulationof a binder; and iii) shaping and curing of the glue-coated finelydivided material to give a molding, or ii′) mixing of the finely dividedmaterial based on lignocellulose and obtained in step i) with athermoplastic polymer and iii′) shaping of the mixture to give amolding.
 10. The process according to claim 9, wherein the treatedmaterial based on lignocellulose is prepared by impregnating anuntreated, finely divided material based on lignocellulose with theaqueous composition and, if appropriate, carrying out a drying and/orcuring at elevated temperature.
 11. The process according to claim 9,wherein the finely divided material is dried to a residual moisturecontent of less than 30%, based on the dry matter, before theglue-coating in step ii).
 12. The process according to claim 10, whereindrying and/or curing is carried out at temperatures in the range from 50to 220° C.
 13. The process according to claim 9, wherein, in step i), atreated finely divided material based on lignocellulose is prepared byimpregnation with the curable, aqueous composition, and thesubstantially uncured material is glue-coated in step ii).
 14. Theprocess according to claim 9, wherein the curable, aqueous compositionis used in an amount such that the curable components absorbed by thefinely divided material are in the range from 1 to 60% by weight, basedon the dry matter of the untreated, finely divided material.
 15. Theprocess according to claim 9, wherein the untreated finely dividedmaterial based on lignocellulose is selected from wood fibers, woodchips and wood shreds.
 16. The process according to claim 9, wherein thefinely divided material based on lignocellulose accounts for at least80% by weight, based on the total weight of the finely divided materialsforming the molding.
 17. The process according to claim 9, wherein thebinder used in step ii) comprises at least one heat-curable binder. 18.The process according to claim 17, wherein the heat-curable binder isused in the form of an aqueous formulation.
 19. The process according toclaim 17, wherein the heat-curable binder is selected from aminoplastresins, phenol resins, isocyanate resins and polycarboxylic acid resins.20. The process according to claim 9, wherein, based on the solid bindercomponents, the binder is used in an amount of from 0.5 to 20% byweight, based on the total weight of the materials forming the molding.21. The process according to claim 9, wherein, in step i), a drying andcuring step is carried out, and the finely divided material thusobtainable is mixed with at least one thermoplastic polymer and themixture is subjected to a shaping process.
 22. The process according toclaim 21, wherein the thermoplastic polymer accounts for from 20 to 90%by weight, based on the total amount of thermoplastic polymer andmolding.
 23. The process according to claim 21, wherein thethermoplastic polymer is selected from poly-C₂-C₆-olefins,poly-C₂-C₄-haloolefins and a mixture thereof.
 24. A molding comprisingfinely divided materials based on lignocellulose, obtainable by aprocess according to claim
 9. 25. A finely divided material based onlignocellulose, obtainable by treating an untreated finely dividedmaterial based on lignocellulose with an aqueous composition, or byimpregnating a wood body with a curable, aqueous composition comprising:a) at least one crosslinkable urea compound from the group consisting ofthe urea compounds H which have at least one N-bonded group of theformula CH₂OR, where R is hydrogen or C₁-C₄-alkyl, and/or a1,2-bishydroxyethane-1,2-diyl group bridging the two nitrogen atoms ofthe urea, precondensates of the urea compound H, and reaction productsor mixtures of the urea compound H with at least one alcohol which isselected from C₁-C₆-alkanols, C₂-C₆-polyols and oligoethylene glycols,and, if appropriate, b) at least one catalyst K effecting crosslinkingof the urea compound.